/**
 * @file boun16.cpp
 * @brief Boundary condition application for contact type 16 slave nodes
 * 
 * This function applies boundary conditions to slave nodes in contact type 16 simulations.
 * It handles various types of boundary conditions including fixed displacements,
 * velocities, and accelerations in both global and local coordinate systems.
 */

#include <vector>
#include <algorithm> // for min/max functions
#include <cmath>

// Forward declaration for load curve function
void LDCSET(std::vector<float>& FVAL, const std::vector<int>& NPC, 
            const std::vector<float>& PLD, const std::vector<int>& IPC, float time);

/**
 * @brief Applies boundary conditions to slave nodes of contact type 16
 * 
 * @param IBCSV Fixed boundary condition indices for slave nodes
 * @param IBVSV Velocity boundary condition indices for slave nodes
 * @param IBA3SV Acceleration boundary condition indices for slave nodes
 * @param IBV3SV Velocity boundary condition indices (3D) for slave nodes
 * @param IBD3SV Displacement boundary condition indices (3D) for slave nodes
 * @param ICODE Boundary condition codes
 * @param BCS Boundary condition transformation matrices
 * @param NVEL Velocity boundary condition parameters
 * @param VBC Velocity boundary condition values
 * @param NAVD3A Acceleration boundary condition node lists
 * @param FAVD3A Acceleration boundary condition factors
 * @param NAVD3V Velocity boundary condition (3D) node lists
 * @param FAVD3V Velocity boundary condition (3D) factors
 * @param NAVD3D Displacement boundary condition (3D) node lists
 * @param FAVD3D Displacement boundary condition (3D) factors
 * @param FVAL Load curve values
 * @param VECFR Local coordinate system vectors
 * @param INV Node inversion mapping
 * @param NSV Slave node list
 * @param NSN Number of slave nodes
 * @param NBPT Number of boundary points
 * @param LSV List of slave nodes to process
 * @param A Acceleration vector (modified in-place)
 * @param V Velocity vector (input)
 * @param U Displacement vector (input)
 * @param NPC Load curve pointers
 * @param PLD Load curve values
 * @param IPC Load curve indices
 * @param IFLAG Operation mode flag (0=setup, 1=apply BCs)
 */
void BOUN16(
    std::vector<int>& IBCSV, std::vector<int>& IBVSV, 
    std::vector<int>& IBA3SV, std::vector<int>& IBV3SV, std::vector<int>& IBD3SV,
    const std::vector<int>& ICODE, const std::vector<std::vector<float>>& BCS,
    const std::vector<std::vector<int>>& NVEL, const std::vector<std::vector<float>>& VBC,
    const std::vector<std::vector<int>>& NAVD3A, const std::vector<std::vector<float>>& FAVD3A,
    const std::vector<std::vector<int>>& NAVD3V, const std::vector<std::vector<float>>& FAVD3V,
    const std::vector<std::vector<int>>& NAVD3D, const std::vector<std::vector<float>>& FAVD3D,
    std::vector<float>& FVAL, const std::vector<std::vector<float>>& VECFR,
    std::vector<int>& INV, const std::vector<int>& NSV, int NSN, int NBPT,
    const std::vector<int>& LSV, std::vector<float>& A, const std::vector<float>& V,
    const std::vector<float>& U, const std::vector<int>& NPC, const std::vector<float>& PLD,
    const std::vector<int>& IPC, int IFLAG)
{
    // Constants from modules (would normally be passed or accessed differently in C++)
    const int NUMRC = 0;  // Number of fixed BCs (should be passed properly)
    const int NUMVC = 0;  // Number of velocity BCs
    const int NACC3D = 0; // Number of 3D acceleration BCs
    const int NVEL3D = 0; // Number of 3D velocity BCs
    const int NDIS3D = 0; // Number of 3D displacement BCs
    const int NDOF = 3;   // Degrees of freedom per node
    const int LENNOD = 16; // Length of node code bitfield
    const int MSKNOD = 0xFFFF; // Mask for node numbers in ICODE
    
    // Time step parameters (would normally be passed properly)
    float DT1 = 0.0f;
    float DT2 = 0.0f;
    float TT = 0.0f;
    
    if (IFLAG == 0) {
        // =============================================================
        // Setup phase: Identify slave nodes with boundary conditions
        // =============================================================
        
        // Initialize inversion mapping
        std::fill(INV.begin(), INV.end(), 0);
        for (int I = 0; I < NSN; I++) {
            INV[abs(NSV[I])] = I + 1; // +1 for 1-based indexing
        }
        
        // Initialize boundary condition indices
        if (NUMRC != 0) std::fill(IBCSV.begin(), IBCSV.begin() + NSN, 0);
        if (NUMVC != 0) std::fill(IBVSV.begin(), IBVSV.begin() + NSN, 0);
        if (NACC3D != 0) std::fill(IBA3SV.begin(), IBA3SV.begin() + NSN, 0);
        if (NVEL3D != 0) std::fill(IBV3SV.begin(), IBV3SV.begin() + NSN, 0);
        if (NDIS3D != 0) std::fill(IBD3SV.begin(), IBD3SV.begin() + NSN, 0);
        
        // Map fixed boundary conditions
        for (int I = 0; I < NUMRC; I++) {
            int NODE = ICODE[I] & MSKNOD;
            int ISV = INV[NODE];
            if (ISV != 0) IBCSV[ISV - 1] = I + 1; // -1 for 0-based indexing
        }
        
        // Map velocity boundary conditions
        for (int I = 0; I < NUMVC; I++) {
            int K = NVEL[I][0]; // First element of NVEL row
            int ISV = INV[K];
            if (ISV != 0) IBVSV[ISV - 1] = I + 1;
        }
        
        // Map 3D acceleration boundary conditions
        for (int I = 0; I < NACC3D; I++) {
            int NODES = abs(NAVD3A[I][0]);
            int ISV = INV[NODES];
            if (ISV != 0) IBA3SV[ISV - 1] = I + 1;
        }
        
        // Map 3D velocity boundary conditions
        for (int I = 0; I < NVEL3D; I++) {
            int NODES = abs(NAVD3V[I][0]);
            int ISV = INV[NODES];
            if (ISV != 0) IBV3SV[ISV - 1] = I + 1;
        }
        
        // Map 3D displacement boundary conditions
        for (int I = 0; I < NDIS3D; I++) {
            int NODES = abs(NAVD3D[I][0]);
            int ISV = INV[NODES];
            if (ISV != 0) IBD3SV[ISV - 1] = I + 1;
        }
    } else {
        // =============================================================
        // Application phase: Apply boundary conditions
        // =============================================================
        float DTX = 0.5f * (DT1 + DT2);
        float DTXI = 1.0f / DTX;
        
        // Apply fixed boundary conditions
        if (NUMRC > 0) {
            for (int II = 0; II < NBPT; II++) {
                int ILSV = abs(LSV[II]);
                int I = IBCSV[ILSV - 1] - 1; // Convert to 0-based index
                if (I < 0) continue;
                
                int NODE = ICODE[I] & MSKNOD;
                int IFIX = ICODE[I] >> LENNOD;
                int ITRIG = IFIX >> 6;
                int J1 = ((IFIX & 32) >> 5) * ITRIG;
                int J2 = ((IFIX & 16) >> 4) * ITRIG;
                int J3 = ((IFIX & 8) >> 3) * ITRIG;
                
                int NJ = NDOF * (NSV[ILSV - 1] - 1);
                A[NJ] = (1 - J1) * A[NJ];
                A[NJ + 1] = (1 - J2) * A[NJ + 1];
                A[NJ + 2] = (1 - J3) * A[NJ + 2];
            }
        }
        
        // Apply velocity boundary conditions
        if (NUMVC > 0) {
            LDCSET(FVAL, NPC, PLD, IPC, TT + 0.5f * DT2);
            
            for (int II = 0; II < NBPT; II++) {
                int ILSV = abs(LSV[II]);
                int I = IBVSV[ILSV - 1] - 1;
                if (I < 0) continue;
                
                int LCUR = NVEL[I][2];
                if (LCUR < 0) continue;
                
                int IDR = NVEL[I][1];
                int K = NVEL[I][0];
                int KK1 = NDOF * (K - 1);
                
                if (IDR <= 3) {
                    float VI = FVAL[LCUR - 1]; // -1 for 0-based index
                    float AIDR = (VI * VBC[I][IDR - 1] - V[KK1 + IDR - 1]) * DTXI;
                    A[KK1 + IDR - 1] = AIDR;
                } else if (IDR == 4) {
                    float VI = FVAL[LCUR - 1];
                    float SCALE = 1.0f / (VBC[I][0] * VBC[I][0] + 
                                 VBC[I][1] * VBC[I][1] + 
                                 VBC[I][2] * VBC[I][2]);
                    float DV = (V[KK1] + A[KK1] * DTX) * VBC[I][0] +
                              (V[KK1 + 1] + A[KK1 + 1] * DTX) * VBC[I][1] +
                              (V[KK1 + 2] + A[KK1 + 2] * DTX) * VBC[I][2];
                    VI = VI - DV * SCALE;
                    
                    A[KK1] += VI * VBC[I][0] * DTXI;
                    A[KK1 + 1] += VI * VBC[I][1] * DTXI;
                    A[KK1 + 2] += VI * VBC[I][2] * DTXI;
                }
            }
        }
        
        // Apply 3D acceleration boundary conditions
        if (NACC3D > 0) {
            LDCSET(FVAL, NPC, PLD, IPC, TT);
            
            for (int II = 0; II < NBPT; II++) {
                int ILSV = abs(LSV[II]);
                int I = IBA3SV[ILSV - 1] - 1;
                if (I < 0) continue;
                
                int NODES = NAVD3A[I][0];
                if (NODES < 0) continue;
                
                int KK1 = 6 * (NODES - 1);
                int IFR = NAVD3A[I][4];
                
                float ALOC[3], VLOC[3];
                if (IFR == 0) {
                    ALOC[0] = A[KK1];
                    ALOC[1] = A[KK1 + 1];
                    ALOC[2] = A[KK1 + 2];
                    VLOC[0] = V[KK1];
                    VLOC[1] = V[KK1 + 1];
                    VLOC[2] = V[KK1 + 2];
                } else {
                    // Transform to local coordinates
                    ALOC[0] = VECFR[IFR - 1][0] * A[KK1] + VECFR[IFR - 1][1] * A[KK1 + 1] + VECFR[IFR - 1][2] * A[KK1 + 2];
                    ALOC[1] = VECFR[IFR - 1][3] * A[KK1] + VECFR[IFR - 1][4] * A[KK1 + 1] + VECFR[IFR - 1][5] * A[KK1 + 2];
                    ALOC[2] = VECFR[IFR - 1][6] * A[KK1] + VECFR[IFR - 1][7] * A[KK1 + 1] + VECFR[IFR - 1][8] * A[KK1 + 2];
                    
                    VLOC[0] = VECFR[IFR - 1][0] * V[KK1] + VECFR[IFR - 1][1] * V[KK1 + 1] + VECFR[IFR - 1][2] * V[KK1 + 2];
                    VLOC[1] = VECFR[IFR - 1][3] * V[KK1] + VECFR[IFR - 1][4] * V[KK1 + 1] + VECFR[IFR - 1][5] * V[KK1 + 2];
                    VLOC[2] = VECFR[IFR - 1][6] * V[KK1] + VECFR[IFR - 1][7] * V[KK1 + 1] + VECFR[IFR - 1][8] * V[KK1 + 2];
                }
                
                // Apply boundary conditions in local coordinates
                int LC1 = NAVD3A[I][1];
                if (LC1 != 0) {
                    float ANEW = FVAL[LC1 - 1] * FAVD3A[I][3];
                    ALOC[0] = ANEW;
                }
                
                int LC2 = NAVD3A[I][2];
                if (LC2 != 0) {
                    float ANEW = FVAL[LC2 - 1] * FAVD3A[I][4];
                    ALOC[1] = ANEW;
                }
                
                int LC3 = NAVD3A[I][3];
                if (LC3 != 0) {
                    float ANEW = FVAL[LC3 - 1] * FAVD3A[I][5];
                    ALOC[2] = ANEW;
                }
                
                // Transform back to global coordinates if needed
                if (IFR == 0) {
                    A[KK1] = ALOC[0];
                    A[KK1 + 1] = ALOC[1];
                    A[KK1 + 2] = ALOC[2];
                } else {
                    A[KK1] = VECFR[IFR - 1][0] * ALOC[0] + VECFR[IFR - 1][3] * ALOC[1] + VECFR[IFR - 1][6] * ALOC[2];
                    A[KK1 + 1] = VECFR[IFR - 1][1] * ALOC[0] + VECFR[IFR - 1][4] * ALOC[1] + VECFR[IFR - 1][7] * ALOC[2];
                    A[KK1 + 2] = VECFR[IFR - 1][2] * ALOC[0] + VECFR[IFR - 1][5] * ALOC[1] + VECFR[IFR - 1][8] * ALOC[2];
                }
            }
        }
        
        // [Additional boundary condition types would follow the same pattern...]
    }
}